#include <stdio.h>
#include <stdlib.h>
unsigned long int fact(int m); // 计算阶乘
int main(int argc, char *argv[])
{
	int n;
	unsigned long int g;
	n = atoi(argv[1]);
	g = fact(n);
	printf("%ld", g);
	return (1);
}
unsigned long int fact(int m)
{
	int i;
	unsigned long int product;
	product = 1;
	for (i = m; i >= 1; i--)
	{
		product *= i;
	}
	return (product);
}
